1. Field of the Invention
The present invention relates to an actuator which transports a workpiece by moving a slider axially by a rotational driving force of a rotational driving source.
2. Description of the Related Art
The present invention proposes an actuator which is used as a means for transporting a workpiece. (See patent literature 1.)
This actuator consists of: a rotational driving source which is located inside an actuator body; a driving force transmitting means, such as a ball screw, which transforms the rotational driving force of the rotational driving source into a linear motion; and a slider which moves along the axis of the actuator body through the driving force transmitting means.
On the top surface of the actuator body is a slit-like groove which is formed axially as an opening and part of the slider, which is movably located in the actuator body, moves along the groove.
A seal member made of elastic material such as rubber is attached to the groove. It closes the groove in order to prevent dust invasion from outside.
The seal member is located so that it can be divided toward both sides of the groove along the moving direction of the slider. While the slider moves along the groove axially, the slider end on the advance direction side of the slider splits the seal member towards both side faces of the groove. This means that even while the slider is moving, the groove remains closed by the seal member. See JP-A No. 201002/1997 (paragraphs 22 to 24).